Buggy code:
public class Composite extends Scrollable { Layout layout ; WINDOWPOS [ ] lpwp ; Control [ ] tabList ; int layoutCount ; int backgroundMode ; Composite ( ) { } public Composite ( Composite parent , int style ) { } Control [ ] _getChildren ( ) { } Control [ ] _getTabList ( ) { } public void changed ( Control [ ] changed ) { } void checkBuffered ( ) { } void checkComposited ( ) { } protected void checkSubclass ( ) { } Control [ ] computeTabList ( ) { } public Point computeSize ( int wHint , int hHint , boolean changed ) { } void copyArea ( GC gc , int x , int y , int width , int height ) { } void createHandle ( ) { } Composite findDeferredControl ( ) { } Menu [ ] findMenus ( Control control ) { } void fixChildren ( Shell newShell , Shell oldShell , Decorations newDecorations , Decorations oldDecorations , Menu [ ] menus ) { } void fixTabList ( Control control ) { } public int getBackgroundMode ( ) { } public Control [ ] getChildren ( ) { } int getChildrenCount ( ) { } public Layout getLayout ( ) { } public Control [ ] getTabList ( ) { } boolean hooksKeys ( ) { } public boolean getLayoutDeferred ( ) { } public boolean isLayoutDeferred ( ) { } public void layout ( ) { } public void layout ( boolean changed ) { } public void layout ( boolean changed , boolean all ) { } public void layout ( Control [ ] changed ) { } void markLayout ( boolean changed , boolean all ) { } Point minimumSize ( int wHint , int hHint , boolean changed ) { } boolean redrawChildren ( ) { } void releaseParent ( ) { } void releaseChildren ( boolean destroy ) { } void releaseWidget ( ) { } void removeControl ( Control control ) { } void resizeChildren ( ) { } boolean resizeChildren ( boolean defer , WINDOWPOS [ ] pwp ) { } void resizeEmbeddedHandle ( int embeddedHandle , int width , int height ) { } void sendResize ( ) { } public void setBackgroundMode ( int mode ) { } void setBounds ( int x , int y , int width , int height , int flags , boolean defer ) { } boolean setFixedFocus ( ) { } public boolean setFocus ( ) { } public void setLayout ( Layout layout ) { } public void setLayoutDeferred ( boolean defer ) { } public void setTabList ( Control [ ] tabList ) { } void setResizeChildren ( boolean resize ) { } boolean setTabGroupFocus ( ) { if ( isTabItem ( ) ) return setTabItemFocus ( ) ; boolean takeFocus = ( ( style ) & ( SWT . NO_FOCUS ) ) == 0 ; <START_BUG> if ( takeFocus && ( ( ( state ) & ( CANVAS ) ) != 0 ) ) { <END_BUG> takeFocus = hooksKeys ( ) ; if ( ( ( style ) & ( SWT . EMBEDDED ) ) != 0 ) takeFocus = true ; } if ( takeFocus && ( setTabItemFocus ( ) ) ) return true ; Control [ ] children = _getChildren ( ) ; for ( int i = 0 ; i < ( children . length ) ; i ++ ) { Control child = children [ i ] ; if ( ( child . isTabItem ( ) ) && ( child . setRadioFocus ( ) ) ) return true ; } for ( int i = 0 ; i < ( children . length ) ; i ++ ) { Control child = children [ i ] ; if ( ( ( child . isTabItem ( ) ) && ( ! ( child . isTabGroup ( ) ) ) ) && ( child . setTabItemFocus ( ) ) ) { return true ; } } return false ; } String toolTipText ( NMTTDISPINFO hdr ) { } boolean translateMnemonic ( Event event , Control control ) { } boolean translateTraversal ( MSG msg ) { } void updateBackgroundColor ( ) { } void updateBackgroundImage ( ) { } void updateBackgroundMode ( ) { } void updateFont ( Font oldFont , Font newFont ) { } void updateLayout ( boolean resize , boolean all ) { } void updateUIState ( ) { } int widgetStyle ( ) { } LRESULT WM_ERASEBKGND ( int wParam , int lParam ) { } LRESULT WM_GETDLGCODE ( int wParam , int lParam ) { } LRESULT WM_GETFONT ( int wParam , int lParam ) { } LRESULT WM_LBUTTONDOWN ( int wParam , int lParam ) { } LRESULT WM_NCPAINT ( int wParam , int lParam ) { } LRESULT WM_PARENTNOTIFY ( int wParam , int lParam ) { } LRESULT WM_PAINT ( int wParam , int lParam ) { } LRESULT WM_PRINTCLIENT ( int wParam , int lParam ) { } LRESULT WM_SETFONT ( int wParam , int lParam ) { } LRESULT WM_SIZE ( int wParam , int lParam ) { } LRESULT WM_SYSCOLORCHANGE ( int wParam , int lParam ) { } LRESULT WM_SYSCOMMAND ( int wParam , int lParam ) { } LRESULT WM_UPDATEUISTATE ( int wParam , int lParam ) { } LRESULT wmNCPaint ( int hwnd , int wParam , int lParam ) { } LRESULT wmNotify ( NMHDR hdr , int wParam , int lParam ) { } }

Fix:
if ( ( ( state ) & ( CANVAS ) ) != 0 ) {